Method of evacuating vessels, more particularly lamps



Patented Nov. 23, 1937 PATENT OFFICE METHOD OF EVACUATING VESSELS, MOREPARTICULABLYIAMPS Carl Trenzen, Venlo, Netherlands No Drawing.Application June 9, 1934, Serial No. 729,908. In Switzerland December 4,1933 '1 Claims.

This invention relates to a method of evacuating vessels, and moreparticularly the bulbs of lamps In the evacuation of vessels,particularly those 5 in which bodies are raised to a very hightemperature, as occurs, for example, in connection with the bulbs oflamps, the evacuation requires to be extended as far as possible inorder to obtain a poor transmission of the heat tothe outer wall of thevessel. Together with the air it is also necessary to expel every traceof steam, as the latter will exert a very destructive efi'ect on thelamp. Despite the care taken it has not been possible up to now toeliminate every trace of v residual gas with the ordinary mechanicalmeans available. For this reason there has been adopted the so-calledgetter process, consisting in the introduction of means which evaporatewhen the lamp is switched on and bind chemically with 0 the residualtraces of gas (Malignani process). For the getter process there areemployed special phosphorous compounds.

In this process the traces of gas, although bound, remain in the bulb,and if conditions are 5 favorable-the P205 formed may again bedecomposed and thus again liberate the gas. This action is liable toshorten the life of the lamp.

In the process according to the invention there is employed for theevacuation of vessels, and

0 more particularly lamp bulbs, a metal carbonyl, which is introducedinto the partially evacuated vessel or bulb. If the vessel is afterwardsheated the carbonyl becomes decomposed. CO is liberated, and this CO,which in contradistinction to 5 ordinary very inert CO is an extremelyactive gas,

combines with the residual gases oxygen, nitrogen and hydrogen.

At a suitable temperature the gases still present in the'filament arealso bound, so that the filament may be subjected to a higher loadwithout eilect on its durability. The evacuation is afterwardscontinued. Upon the decomposition the metal may be allowed to remain inthe gaseous form dependent on the temperature employed,

; so that the same is also included by the vacuum, or it may bedeposited on to a particularly heated part of the vessel.

In the case of lamp bulbs precautions will be taken that this deposit isproduced only at a point having no detrimental efle'ct, or the heatingwill be so performed that the metal is deposited in the form of a finelydistributed reflector in such a manner that it reflects the light of thefilament towards the side where the same is required.

In carrying the invention into efl'ect the process such as nickelcarbonyl Ni(C0)4, molybdenum 5 1 carbonyl M0(CO )2 or fen'ocarbonyl. Thelamp is afterwards subjected to the decomposing temperature at thepressure prevailing. The metal carbonyl is decomposed, and the liberatedmetal produces at ,the point of heating a bright reflector. The veryactive CO combines spontaneously with the residual traces of oxygen,nitrogen and hydrogen in the interior of the bulb and the filament,which gases may be much more readily expelled than if the same adheresingly to the glass wall. Whereas, therefore, in the known getterprocesses, 1 the gases remain in bound form in the lamp, and may alwaysexert a detrimental effect on the life of the lamp, the same in the caseof the invention are expelled from the lamp. 2 The metallic reflectorremaining in the'bulb nevertheless also acts as getter, since owing toits fine distribution it is able to absorb and render harmless the,traces of injurious gas emerging later from the filament or the edge ofthe glass. By suitably heating the bulb it is also possibleto apply themetallic reflector to points where the same is useful, 1. e., may beutilized for reflecting the light in a certain direction.

In place of one single metal carbonyl it is also possible to employ amixture of diflerent carbonyls.

In the above example reference has, merely been made to the evacuation01 a lamp bulb. It is obvious. however, that this method may be employedboth for evacuated as well as gas-filled lamps It has been found that bythe simultaneous use of phosphorous as a getter in conjunction with ametal carbonyl the eflect above referred to is obo tained in the mostsimple and reliable fashion, socalled phosphorous solution beinginjected or sprayedon for example together with a metal carbonyl.Molybdenum carbonyl and tungsten carbonyl have been found very effectiveas addition to phosphorous solution. Embodiment in the form of a doublespiral is also advisable, as the surfacefor reception of the getter isformed accordingly.

What I claim as new and desire to secure by Letters Patent is: I

1. Amethodof evacuating vessels,- and more particularly lamp bulbs,which consists in partial- 1y evacuating the vessel, then introducing atleast one metal carbonyl, and thereupon heating u in claim' 1, in whichthe temperature employed for decomposing the metal carbonyl isrsuch thatthe metal remains, in a gaseous state and is removed upon completing theevacuation.

3. A method of evacuating vessels, and more particularly lamp bulbs,which consists in partially evacuating the vessel, then introducinnickel carbonyl into the said vessel, heating the said vessel to causedecomposition .of the said nickel carbonyl, so that the air and tracesof gas combine with the liberated CO, and then completing the evacuationof the said-vesel.

4. A method of evacuating vessels, and more particularly lamp bulbs,which consists in partially evacuating the vessel, then introducingmolybdenum carbonyl into the said'vessel, heating the said vessel tocause decomposition of the said molybdenum carbonyl, so that the air andtraces of gas combine with the liberated C0, and then completing theevacuation of the said vessel.

5 A method of evacuating vessels, and more particularly lamp bulbs,which consists in partially evacuating the vessel, then introducingferrocarbonyl into the said vessel, heating the said vessel to causedecomposition of the said ferrocarbonyl, so that the air and traces ofgas combine with the liberated CO, and then completing the evacuation ofthe said vessel.

6. A method of evacuating vessels, and more particularly lamp bulbs, asclaimed in claim 1, in which a mixture of carbonyls and phosphoroussolution is introduced into the said vessel.

7. A method of evacuating vessels, and more particularly lamp bulbs,which consists in partially evacuating the vessel, then introducing acarbonyl of a metal of the group consisting of nickel, molybdenum, iron,tungsten, into the said vessel, heating the said vessel to causedecomposition of the said carbonyl, so that the air and traces of gascombine with the liberated CO, and then completing the evacuation of thesaid vessel.

' CARL TRENZEN.

